原位条件下无烟煤热解产物随温度变化研究

Study on variation of anthracite pyrolysis products with temperature under in-situ conditions

为了研究深埋深无烟煤原位热解采气过程中的气体产物产量特性,采用高温高压三轴试验仪和气相色谱仪,获得100~600℃内无烟煤的热解产气量和产物,分析了产物和渗透性之间的关系。研究表明热解产气量随温度的变化可分为4个阶段:在100~200℃范围内为第1阶段(脱气阶段),无烟煤产生少部气体,析出的气体主要N_(2)和O_(2);在300~400℃范围内为第2阶段(热解起始阶段),无烟煤进一步热解,气体产量进一步上升,气体主要由煤热解产生的CH_(4)、CO_(2)、H_(2)和C_(2)H_(6)等组成,400℃是热解产气量第1个峰值;在400~500℃范围内为第3阶段(热解阶段),由于无烟煤中有机物质的热稳定性所致,导致产气量降低;在500~600℃范围内为第4阶段(裂解阶段),热解气体产量又一次持续增加,该部分气体主要为CH_(4)、C_(2)H_(6)和H_(2);渗透率受热解过程中的产物影响,300℃是低渗透煤层注热开采瓦斯合理的注热温度。

To study the gas product yield characteristics during in-situ pyrolysis of deep buried anthracite for gas extraction,high-temperature and high-pressure triaxial tester and gas chromatography were used to obtain the pyrolysis gas yield and products of anthracite in the range of 100-600℃.The relationship between product and permeability was analyzed.The study showed that the variation of pyrolysis gas yield with temperature can be divided into four stages:the first stage(degassing stage)from 100℃ to 200℃,where the anthracite produces small amounts of gas and the precipitated gas is mainly N_(2) and O_(2).The second stage ayayrolysis initiation stage)from 300℃ to 400℃,where the anthracite coal is further pyrolyzed and the gas yield further increases,and the gas is mainly composed of CH_(4),CO_(2),H_(2) and C_(2)H_(6) produced by coal pyrolysis.400℃ is the first peak of pyrolysis gas production.The range of 400-500℃ is the third stage(pyrolysis stage),due to the thermal stability of organic substances in anthracite,resulting in lower gas production.The range of 500-600℃ is the fourth stage(cracking stage),and pyrolysis gas production once again continues to increase.The permeability is influenced by the gas yield and gas production during pyrolysis.